By TRIP GABRIELAlberta Jones is the civil rights pioneer almost no one knows. She was Louisville’s first black prosecutor and negotiated the first fight contract for Muhammad Ali, her neighbor. She registered thousands of African-American voters in the 1960s and paved the way for a ban on racial discrimination by local theaters and lunch counters.

One person who was astonished she had never heard of Ms. Jones was a professor named Lee Remington, who began research for a biography four years ago. The more Professor Remington learned, the more she became desperate to discover what no one has ever learned: who was responsible for Ms. Jones’s death in 1965, when, at 34, she was brutally beaten and thrown into the Ohio River to drown.

Poring over 1,600 pages of police files, Professor Remington, a lawyer and political scientist, shifted from mere history to what she calls “a quest for justice.’’ She laid out what she believed were overlooked clues to the murder in a long letter last year to the Louisville police, who agreed to reopen the case. The Justice Department’s civil rights division also stepped in.

But even with renewed interest in the case, it is unclear whether there is any real chance — 52 years after Ms. Jones died, when witnesses are deceased and evidence has vanished — of finding out who killed her and why.

“I believe her death was directly related to the work she was doing,” said Professor Remington, who teaches at Bellarmine University in Louisville. “If there was a list of people she would have stood up to and made mad, it would be five pages long.”

The Louisville Metro Police Department said this week that there have been few breakthroughs. “We still haven’t established enough probable cause to say one person or another did it,” Sgt. Nicholas Owen, the lead investigator, said.

Ms. Jones, who never married, is survived by a sister, Flora Shanklin, now 81. She believes earlier investigators ignored clues and buried evidence because of indifference to the murder of a prominent African-American, or because the killers were protected by authorities.

Ms. Shanklin recalled her sister saying she was regularly hassled by a white court officer at work. One day Ms. Jones got frustrated, Ms. Shanklin said, and “hit him with her briefcase.”

Ms. Jones’s name is absent from the annals of civil rights martyrs of the 1960s, perhaps because there is no clear evidence that her death was racially or politically motivated. Louisville, on the dividing line between North and South, largely avoided the harshest violence of the era, like church bombings and the murder of civil rights workers by white supremacists, and today does not have the immediate resonance of, say, Birmingham, Ala.

Still, the city Ms. Jones returned to in 1959 after graduating from Howard University School of Law was deeply segregated. Blacks could not enter movie theaters or restaurants in the city’s commercial heart, Fourth Street, or try on clothes at department stores.

Ms. Jones helped establish the Independent Voters Association, which registered 6,000 African-Americans. Voting as a bloc, blacks replaced the mayor of Louisville and many of the city’s aldermen in 1961. Two years later these officials outlawed racial discrimination in businesses, the first public accommodation ordinance of its kind in the South.

“We taught the Negros how to use that voting machine,” Ms. Jones told The Courier-Journal in March 1965. It was shortly after she became a city prosecutor, the first African-American and first woman of any race in that job in Louisville. “When I got back home a lot of people said, ‘You’ve got two strikes against you: You’re a woman and you’re a Negro,’” she told the newspaper. “Yeah, but I’ve still got one strike left, and I’ve seen people get home runs when all they’ve got left is one strike.’’

Ms. Jones lived in Louisville’s majority-black West End with her mother and sister, just a couple of blocks from the young Cassius Clay. In 1960, the future Muhammad Ali hired her to represent him when he turned professional. She negotiated a contract with 11 white millionaires, the famous Louisville Sponsoring Group. Protective of her client, she insisted that 15 percent of his winnings be held in trust until he turned 35, with Ms. Jones serving as a co-trustee. Today the contract hangs on the wall of the Muhammad Ali Center in Louisville.

Ms. Shanklin said her sister took the boxer to buy a pink Cadillac at a downtown landmark, Brown Brothers Cadillac. “He used to come by the house and take my son and daughter to school” in the car, she recalled.

On the night Ms. Jones was murdered, Aug. 5, 1965, witnesses saw two black males drag a screaming woman into the back seat of a car like the Ford Fairlane Ms. Jones was driving, according to police records. Her body, with trauma to the head and face, was retrieved from the river near an amusement park in the West End. A large quantity of blood stained the back seat of the Fairlane, discovered nearby, which she had rented while her own car was in the shop.Ms. Shanklin believes that whoever murdered her sister was paid by others. “I don’t know who, but she stepped on some toes,” she said.

In all the years the police have investigated Ms. Jones’s murder, reopening the case twice, they have never developed a dominant theory about suspects or a motive, according to records and Sergeant Owen, the current investigator.

One theory pursued in the 1960s was that she was killed by the Nation of Islam because its leader, Elijah Muhammad, coveted the 15 percent of Muhammad Ali’s earnings that Ms. Jones managed. A black detective working the case at the time, who was interviewed by the police in the 1980s, said that when he was pursuing this angle, his wife received a death threat.

Sergeant Owen said the Nation of Islam theory has never been substantiated. “I haven’t seen any evidence to indicate that aside from hearsay,” he said.

Almost all physical evidence from 1965 has been lost. In 2008, police got what looked to be a major break: a match on a fingerprint found on the Fairlane Ms. Jones was driving.

The print, matched by the Federal Bureau of Investigation, belonged to a Louisville man who was 17 at the time of Ms. Jones’s death. He admitted in 2008 to detectives that he used to hang out in a park with friends one block from where witnesses saw the woman dragged into the back of a car.

But with no more evidence, the prosecutor at the time, R. David Stengel, declined to bring charges and declared the case closed “for the foreseeable future.”

In an interview last week, the man linked to the car, now 70, said that he knew nothing of Ms. Jones’s murder. “I didn’t touch that lady,” he said. “I don’t know who did. That’s all I can say.” His explanation for the fingerprint was that he used to hitchhike as a teenager and must have been picked up by someone who had rented the Fairlane before Ms. Jones. The Times is withholding the man’s name because police do not consider him a suspect.

Sergeant Owen said he was at a loss for new leads. He had hoped, as he interviewed old suspects as well as people who had been overlooked in the 1960s, that time would have loosened their tongues.

“I really don’t have a theory,” he said. “It could be anybody. I was hoping for guilt to weigh on somebody and have them confess. That hasn’t happened yet.”

A spokeswoman for the Justice Department, Lauren Ehrsam, confirmed that its civil rights office was reviewing the issues raised by Professor Remington about the case. Sergeant Owen said he had heard nothing from Washington.

Next month a Louisville civic group plans to hang a giant banner with Ms. Jones’s portrait on a bank building on Muhammad Ali Boulevard. It will join other portraits downtown honoring prominent people with Louisville roots, including Diane Sawyer and Colonel Harland Sanders of fast-food fame.

Professor Remington hopes the banner will prick someone’s memory — or conscience — about what happened to Ms. Jones 52 years ago. “She spent her whole life fighting for others,’’ she said. “It’s time somebody started fighting for her.”